JP4836645B2 - Flue gas denitration equipment and control method of flue gas denitration equipment - Google Patents

Description

  The present invention relates to a flue gas denitration facility for removing nitrogen oxides in exhaust gas and a method for controlling the flue gas denitration facility.

Since exhaust gas discharged from boilers used in thermal power plants, etc. contains nitrogen oxides (NO _x ), a flue gas denitration facility consisting of a denitration device, ammonia injection device, NO _x meter, etc. after removal of NO _x with, and the air discharging exhaust gas from the stack. Generally the NO _x removal, blowing ammonia into the exhaust gas, called selective catalytic reduction method, the NO _x on the catalyst is reacted with ammonia, a method of decomposing the NO _x to nitrogen and water is used. Specifically, the exhaust gas was provided denitration apparatus having a denitration catalyst in an exhaust gas duct leading to the chimney, the ammonia is injected into the inlet side of the exhaust in the gas duct of the denitration apparatus, for removing NO _x in denitrator.

Since the removal of NO _x in the exhaust gas causes the NO _x in the exhaust gas to react with the ammonia injected from the outside on the catalyst, it is important to adjust the injection amount of ammonia. When the amount of ammonia to be injected is insufficient, NO _x in the exhaust gas cannot be sufficiently removed. On the other hand, when the ammonia injection amount becomes excessive, the ammonia becomes excessive and is released to the atmosphere as leaked ammonia. Conventionally, injection volume generally ammonia, measurements of the inlet concentration of NO _x denitration apparatus, the measured value of the outlet concentration of NO _x denitration apparatus, the process gas quantity, and the basic and the set value of the outlet NO _x of the denitration device Then, the ammonia injection amount was calculated, and correction was made in consideration of boiler load fluctuations and the like. In addition, further measures the concentration of NO _x chimney inlet, calculates the injection amount of ammonia by adding the data, there is a method of controlling.

Conventional ammonia injection rate control method on the other hand, denitrification device inlet NO _x meter, a large response speed delay of denitrator outlet NO _x meter, possibly exhaust NO _x concentration of the denitration device outlet exceeds hunting regulated value There is a method for solving this problem (see, for example, Patent Document 1).
JP 2001-104755 A

The technique described in Patent Document 1 is intended to propose a solution to the exhaust NO _x concentration of the denitration device outlet may exceed the hunting regulated value, also the other problem in denitrification equipment is there. Comprising an exhaust gas analyzer for measuring the concentration of NO _x chimney inlet, when the concentration of NO _x chimney inlet port In the flue gas denitration equipment be operated such that less environmental regulation value, to control the ammonia injection amount the inlet concentration of NO _x is calculated ammonia Note amount set value based on the basis of the denitration apparatus, the outlet concentration of NO _x denitration apparatus, and calculates the respective correction value on the basis of the concentration of NO _x chimney inlet, adding this To determine the ammonia injection amount set value. Therefore, calibration of the exhaust gas analyzer for measuring the concentration of NO _x chimney inlet, a method of operating a flue gas denitration equipment during inspection becomes a problem.

Calibrate the exhaust gas analyzer for measuring the concentration of NO _x chimney inlet, when inspection, the output of the exhaust gas analyzer varies greatly, when calculating the ammonia injection quantity setting value is the concentration of NO _x chimney inlet The correction value based on it is set to zero. This is performed based on the ON signal of the calibration check switch of the exhaust gas analyzer. Therefore calibrate the exhaust gas analyzer, during inspection, can not be optimally controlled ammonia injection amount, temporarily concentration of NO _x chimney inlet is likely to exceed the environmental regulation value. Moreover, calibrating the exhaust gas analyzer for measuring the concentration of NO _x chimney inlet, during inspection, the alarm circuit of the chimney inlet concentration of NO _x height from the viewpoint of preventing false alarms is blocked.

Therefore operator while checking the concentration of NO _x chimney inlet in recorder, and manual intervention if necessary, the ammonia injection amount as the concentration of NO _x chimney inlet does not exceed the environmental regulations value It needs to be adjusted. Driving while monitoring with a recorder is a heavy burden on the operator. The calibration of the exhaust gas analyzer, after inspection completed and Kiriwasureru calibration test switch, for alarm chimney inlet concentration of NO _x height is in the state of being cut off, concentration of NO _x in the chimney inlet port environmental regulation value The operator may not notice this even if it exceeds.

The present invention has been made in view of such circumstances, an object of the present invention, the calibration of the exhaust gas analyzer for measuring the concentration of NO _x chimney inlet flue gas denitration equipment, inspection during and calibration operation after inspector It is an object of the present invention to provide a flue gas denitration facility that can reduce the monitoring load and a method for controlling the flue gas denitration facility.

The present invention includes a denitration apparatus for removing NO _x in the exhaust gas disposed in the exhaust gas duct, and ammonia injection unit for injecting ammonia into the inlet portion of the denitration apparatus, for measuring the inlet concentration of NO _x of the NO x removal apparatus a denitrification device inlet gas analyzer, a denitrification device outlet gas analyzer to measure the outlet concentration of NO _x of the NO x removal apparatus, the chimney inlet gas analyzer for measuring the concentration of NO _x inlet chimney for exhaust gas atmosphere release, A flue gas denitration facility comprising a calibration / inspection switch that outputs a signal during calibration and inspection of the chimney inlet gas analyzer, and a control device that controls the output of an ammonia injection amount and an alarm, wherein the denitration device inlet gas analysis meter, the denitration apparatus outlet gas analyzer, and the ammonia injection amount based on the concentration of NO _x measurements of the chimney inlet gas analyzer controlling, concentration of NO _x in the chimney inlet port driver tube It outputs an alarm when it exceeds the value, the chimney inlet gas analyzer calibration, during inspection, ammonia injection based on the denitrator inlet gas analyzer, and NO _x concentration measurement value of the denitrification apparatus outlet gas analyzer to control the amount, NO _x concentration of said chimney inlet is a flue gas denitration equipment when exceeding the operating control value continuously predetermined interval of time, wherein the controller controls so as to output an alarm.

The present invention is an inlet concentration of NO _x denitration apparatus for removing NO _x in the exhaust gas, the outlet concentration of NO _x of the NO x removal apparatus, and to measure the concentration of NO _x chimney inlet, concentration of NO _x measurement of this 3-point controls ammonia injection amount to the basis of the value denitrator, wherein when the concentration of NO _x chimney inlet exceeds the operation control value outputs an alarm, chimney inlet to measure the concentration of NO _x of the chimney inlet calibration of gas analyzers, time of inspection, the inlet concentration of NO _x measurements of the denitration apparatus, and the control of ammonia injection amount to the denitrification device based on the outlet concentration of NO _x measurements of the denitration apparatus, wherein the chimney inlet concentration of NO _x is a method of controlling a flue gas denitration equipment when exceeding the operating control value continuously predetermined interval of time, wherein the controller controls so as to output an alarm.

Exhaust gas denitration apparatus of the present invention controls the ammonia injection amount to the denitrification device, under a predetermined condition, the concentration of NO _x measurements chimney inlet, when it exceeds the operation control value, and outputs an alarm a control unit for controlling so that the calibration of the chimney inlet gas analyzer for measuring the concentration of NO _x chimney inlet (exhaust gas analyzer), during inspection, the concentration of NO _x chimney inlet, predetermined interval of time continued When the operation management value is exceeded, control is performed so as to output an alarm, so that the operator does not need to monitor with a recorder as in the conventional case, and the monitoring load is reduced. The calibration of the exhaust gas analyzer for measuring the concentration of NO _x chimney inlet, after inspection completion, even if the off forgotten the calibration test switch of the exhaust gas analyzer, unlike the conventional denitration equipment chimney inlet concentration of NO _x height An alarm is issued so that the operator can notice this and take appropriate action.

FIG. 1 is a diagram showing a schematic configuration of a flue gas denitration facility 1 as an embodiment of the present invention. The flue gas denitration facility 1 includes an ammonia injection device 3 that injects ammonia into an inlet portion of the denitration device 2, an exhaust gas analyzer 4 that measures the concentration of NO _x in the exhaust gas, and a control device 5. The exhaust gas discharged from the boiler is guided to the exhaust gas duct 11, and the NO _x in the exhaust gas is a denitration device 2 installed in the exhaust gas duct 11, and the concentration of NO _{x at} the inlet of the chimney 12 is less than the operation control value. Removed until The operation management value is lower than the environmental regulation value, and the operation management value that is lower than the environmental regulation value is used to prevent the NO _X concentration from exceeding the environmental regulation value. Denitration apparatus 2 is provided with a catalyst, and NO _x of ammonia and the exhaust gas supplied to the inlet of the denitration apparatus 2 is reacted over a catalyst to decompose the NO _x into nitrogen and water.

The exhaust gas from which NO _x has been removed by the denitration device 2 is sent to the electric dust collector 13 through the exhaust gas duct 11, where the dust contained in the exhaust gas is removed, and then released into the atmosphere through the chimney 12. Between the exhaust gas duct 11 connecting the denitration device 2 and the electric dust collector 13, an air preheater 14 for preheating the combustion air of the boiler using the heat of the exhaust gas is disposed. In the present embodiment, air is mixed into the exhaust gas that has exited the denitration device 2 as will be described later. NO _x in the exhaust gas, since the concentration of NO _x in oxygen-converted chimney inlet portion is subject to regulation, the following, concentration of NO _x (oxygen converted value) of the chimney inlet is at the chimney inlet oxygenated converted It is intended to mean the NO _x concentration.

The ammonia injection device 3 includes an ammonia injection pipe 31 for injecting ammonia into the exhaust gas duct 11 and an ammonia injection amount adjusting valve 32 for adjusting the ammonia injection amount. The valve opening degree of the ammonia injection amount adjusting valve 32 is performed based on a command from the control device 5. The control device 5 calculates the injection amount of ammonia, outputs a control signal for controlling the injection amount of ammonia, communicates with the alarm device 40, and outputs a warning signal to the alarm device 40. When the concentration of NO _x (oxygen converted value) is determined to exceed the operating control value, under a predetermined condition, it sends a signal to the alarm device 40.

FIG. 2 is a diagram for explaining the control procedure of the ammonia injection amount of the control device 5. The control unit 5, denitration concentration of NO _x of the inlet portion of the apparatus 2, a denitration apparatus concentration of NO _x in the outlet portion of 2, and the exhaust gas analyzer 4 (4a to measure the concentration of NO _x chimney inlet, 4b, 4c ) concentration of NO _x data is sent from the control unit 5, by using the set value with these data, as the concentration of NO _x in the exhaust gas at the chimney inlet (oxygen converted value) is equal to or less than the operation control value The ammonia injection amount is calculated, and a control signal is sent to the ammonia injection device 3. Specifically, the control unit 5, the inlet concentration of NO _x measurements of denitrator 2, to calculate the ammonia injection amount set value base 20 from the exhaust gas amount, and the molar ratio and the like. The calculated NOx removal outlet _NO x PI correction value 21 by using the outlet concentration of NO _x measurements of denitrator 2, _{O 2} converted PI correction value chimney inlet NO _x with inlet concentration of NO _x measurements chimney (oxygen (Converted PI correction value) 22 is calculated. These values are added by the adders 23 and 24, the ammonia injection amount set value 25 is calculated, a difference from the actual ammonia flow rate is used as an ammonia injection amount adjustment valve opening command, and a control signal is sent to the ammonia injection amount adjustment valve 32. send.

The flue gas denitration facility 1 shown in the present embodiment includes an air preheater 14 between the denitration device 2 and the electric dust collector 13. Air preheater 14 is for preheating the air for boiler combustion by utilizing the waste heat of the exhaust gas, for here from air boiler combustion enters the exhaust gas duct 11, NO _x concentration at the chimney inlet (raw ) Is detected low. NO _x in the exhaust gas, since the concentration of NO _x in oxygen-converted chimney inlet (oxygen converted value) it is necessary to remove the NO _x to be equal to or less than the operation control value, O ₂ chimney inlet NO _x A converted PI correction value (oxygen conversion PI correction value) 22 is used for calculation and control of the ammonia injection amount.

In flue gas denitration equipment 1 constructed as mentioned above will be explained a control method of the control device 5 when calibrating the exhaust gas analyzer 4c to measure the concentration of NO _x chimney inlet. The exhaust gas analyzer 4c is normally calibrated once a week, and the calibration time per time is about 30 minutes. When calibrating the exhaust gas analyzer 4c to measure the concentration of NO _x chimney inlet, in order to calibrate the exhaust gas analyzer 4c using model gas containing air, or a high concentration of NO _x, the output of the exhaust gas analyzer 4c Fluctuates greatly. Therefore, similarly to when not calibrate the exhaust gas analyzer 4c, and calculates the O ₂ conversion PI correction value 22 for the chimney inlet NO _x based on the output of the exhaust gas analyzer 4c, which during ammonia injection quantity setting value calculation When the correction value is used, the ammonia injection amount setting value 25 varies greatly.

Therefore, when calibrating the exhaust gas analyzer 4c chimney inlet portion, the calculation of ammonia injection amount set value 25 inputs the O ₂ conversion PI correction value 22 for the chimney inlet NO _x as zero. Check in proof of exhaust gas analyzer 4c is performed based on the signal of the calibration test switch (SW) 26 of the exhaust gas analyzer 4c, an ON signal is output switch 27, O ₂ chimney inlet NO _x The converted PI correction value 22 is set to zero. During calibration of the thus chimney inlet of the exhaust gas analyzer. 4c, the O ₂ conversion PI correction value 22 for the chimney inlet NO _x as zero, for calculating the ammonia injection amount set value 25, optimally control the ammonia injection amount It can not be temporarily fear is that the concentration of NO _x chimney inlet (oxygen converted value) exceeds the environmental regulation value. In this case, the control unit 5, the alarm device 40 under a predetermined condition sends an alarm signal chimney inlet NOx concentration high, NO _x concentration of the chimney inlet (oxygen converted value) exceeds the operation control value to operator Notify that there is. These are the same when checking the exhaust gas analyzer 4c. Next, the alarm control procedure of the control device 5 will be described.

Figure 3 is a circuit diagram illustrating an alarm sequence 50 for sending an alarm signal chimney inlet concentration of NO _x height to the control device 5 is the alarm device 40. In FIG. 3, 54 and 55 are AND circuits, and an output signal “1” is output only when the input signals are all “1”, and “0” is output otherwise. An OR circuit 56 outputs an output signal “1” if at least one of the input signals is “1”, and outputs an output signal “0” only when all the input signals are “0”. The A knot circuit 57 inverts the input signal and the output signal. 58 is an on-relay, and only when the input signal “1” is continuously input for a predetermined time, the output signal “1” is output after the predetermined time has elapsed, and in other cases, the output signal “0” is output. The

Alarm sequence 50, exhaust gas analyzer 4c chimney inlet port calibration signal 51 of the calibration test switch 26 which indicates whether or not is being inspected, the burner ignition signal 52 of the boiler 10, and a chimney inlet concentration of NO _x (oxygen A signal 53 indicating whether or not the (converted value) exceeds the operation management value is input. The alarm sequence 50 will be described separately for (1) when the exhaust gas analyzer 4c at the chimney inlet is not being calibrated as in normal operation, and (2) when the exhaust gas analyzer 4c at the chimney inlet is being calibrated.

(1) When the exhaust gas analyzer 4c at the chimney entrance is not being calibrated, the signal 51 of the calibration check switch 26 of the exhaust gas analyzer 4c is “0”, and after being inverted to “1” by the knot circuit 57 through the route 60 The OR circuit 56 is entered through the route 61, and the input signal “1” is inputted to the AND circuit 55 through the route 62. Since the concentration of NO _x chimney inlet (oxygen converted value) is more than the operation control value signal 53 outputs "1", the root 65, a signal of "1" through route 66 is inputted to the AND circuit 55 . As a result, the AND circuit 55 is established, an alarm signal chimney inlet concentration of NO _x height 70 is output. When exhaust gas analyzer 4c of the thus chimney inlet is not in calibration, regardless of whether the burner ignition signal 52 of the boiler, the concentration of NO _x chimney inlet (oxygen converted value) exceeds the operation control value immediately alarm signal 70 chimney inlet concentration of NO _x height is outputted.

(2) When the exhaust gas analyzer 4c at the chimney inlet is being calibrated, the signal 51 of the calibration check switch 26 of the exhaust gas analyzer 4c is “1”, and the AND circuit 54 is set to “1” through the route 60 and the route 64. A signal is input. When the boiler is in operation, the boiler burner ignition signal 52 is “1”, and a signal “1” is input to the AND circuit 54 through the route 63. The signal 53 when the concentration of NO _x chimney inlet (oxygen converted value) exceeds the operation control value, outputs a signal "1", the concentration of NO _x chimney inlet (oxygen converted value) is continued for 10 minutes If the operation management value is continuously exceeded, the online 58 outputs the signal “1”, and the signal “1” is input to the AND circuit 54 through the route 67. Since the AND circuit 54 is established in this state, the signal “1” is input to the AND circuit 55 through the route 68, the OR circuit 56, and the route 62. On the other hand, the the concentration of NO _x chimney inlet (oxygen converted value) exceeds the operation control value at the time, the root 65, the signal "1" is inputted to the AND circuit 55 through the route 66, the AND circuit 55 There satisfied, NO _x concentration high alarm signal 70 of the chimney inlet is output.

When exhaust gas analyzer 4c of the thus chimney inlet is in calibration, in order to alarm signal 70 chimney inlet concentration of NO _x height is output, it is necessary to satisfy some conditions. First, the burner must be ignited. If the burner is not ignited, that is, when the boiler is not running, so the exhaust gas is not discharged, NO _x density-high alarm signal chimney inlet is not required. When exhaust gas analyzer 4c chimney inlet is in calibration, in order to alarm signal of the NO _x concentration high chimney inlet is output, further, concentration of NO _x in the chimney inlet (oxygen converted value) is 10 minutes It is necessary to continue to exceed the operation control value. During the calibration of the flue gas analyzer 4c at the chimney inlet, the output largely fluctuates as described above. However, the normal calibration adjusts the zero and span alternately, so the exhaust gas analysis at the chimney inlet even during calibration of the meter 4c, nO _x concentration of the chimney inlet (oxygen converted value) does not become a high state continuously over 10 minutes. If chimney concentration of NO _x inlet (oxygen converted value) exceeding driving control value continuously for more than 10 minutes, which is not associated with the calibration of the exhaust gas analyzer 4c, the concentration of NO _x in the exhaust gas It can be said that it is high.

Since the regulation value of NO _x concentration in exhaust gas is managed as a time average value, even if the NO _x concentration in exhaust gas temporarily exceeds the operation control value, the environmental regulation value, which is a time average value, is set. it can be addressed by removing the NO _x to be below. Nevertheless during calibration of exhaust gas analyzer 4c chimney inlet, when the concentration of NO _x in the exhaust gas over a long period of time exceeds the operation control value, it can not be removed NO _x to be below the environmental standard value If there is also, in the present invention, when the chimney concentration of NO _x inlet (oxygen converted value) exceeding driving control value continuously for more than 10 minutes, and controls so as to issue a warning, like this Don't worry. The time to issue an alarm when the concentration of NO _x chimney inlet (oxygen converted value) exceeds the operating control value continuously is not intended to be limited to 10 minutes. It is desirable that a short time, since naturally requires a certain time in the calibration of the exhaust gas analyzer, too short to the concentration of NO _x and high alarm signal 70 of the chimney inlet with the calibration of the exhaust gas analyzer output Will be. Therefore, this time may be determined in relation to the calibration procedure of the exhaust gas analyzer. These are the same when checking the exhaust gas analyzer 4c.

By setting the alarm sequence as described above, may be the concentration of NO _x chimney inlet (oxygen converted value) is appropriately monitors whether exceeds a operation control value. In particular exhaust gas analyzer 4c calibration chimney inlet, even during inspection, that the concentration of NO _x chimney inlet (oxygen converted value) can be known by the warning whether exceeds a operation control value, not in the conventional denitrification equipment, operator can concentration of NO _x chimney inlet (oxygen converted value) is easily to monitor whether or not exceeding the operational control value. Further, by using the alarm sequence 50 of the present invention, even if off forgotten the calibration test switch 26 of the exhaust gas analyzer 4c, exceeds the operation control value the concentration of NO _x chimney inlet (oxygen converted value) is continued for 10 minutes Continue If, because the alarm signal 70 chimney inlet concentration of NO _x height is output, the operator notices that the calibration test switch 26 the exhaust gas analyzer is off forgotten during cause investigation against this warning, the calibration of the exhaust gas analyzer The inspection switch 26 can be turned off. The normal state control can be performed by turning off the calibration check switch 26 of the exhaust gas analyzer.

It is a figure showing a schematic structure of flue gas denitration equipment 1 as one embodiment of the present invention. It is a figure for demonstrating the control point of the ammonia injection amount of the control apparatus 5 of the flue gas denitrification equipment 1 as one Embodiment of this invention. The control unit 5 of the denitration equipment 1 as an embodiment of the present invention, is a circuit diagram illustrating an alarm sequence 50 for sending an alarm signal chimney inlet concentration of NO _x and high alarm device 40.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flue gas denitration equipment 2 Denitration apparatus 3 Ammonia injection apparatus 4 Exhaust gas analyzer 5 Control apparatus 11 Exhaust gas duct 26 Calibration check switch

Claims (2)

A denitration device for removing NO _x in the exhaust gas disposed in the exhaust gas duct;
An ammonia injection device for injecting ammonia into the inlet of the denitration device;
A denitrification device inlet gas analyzer to measure the inlet concentration of NO _x of the NO x removal apparatus,
A denitration apparatus outlet gas analyzer to measure the outlet concentration of NO _x of the NO x removal apparatus,
A chimney inlet gas analyzer that measures the NO _x concentration at the inlet of the chimney that releases exhaust gas to the atmosphere;
A flue gas denitration facility comprising a calibration / inspection switch that outputs a signal during calibration and inspection of the chimney inlet gas analyzer, and a control device that controls the output of the ammonia injection amount and an alarm,
The denitrification device inlet gas analyzer, said denitration apparatus outlet gas analyzer, and by controlling the ammonia injection amount based on the concentration of NO _x measurements of the chimney inlet gas analyzer, concentration of NO _x is operation control value of the chimney inlet the outputs an alarm when it exceeds, the chimney inlet gas analyzer calibration, during inspection, ammonia injection amount based on the NOx removal system inlet gas analyzer, and NO _x concentration measurement value of the denitrification apparatus outlet gas analyzer controls, NO _x concentration of said chimney inlet section, flue gas denitration equipment when exceeding the operating control value continuously predetermined interval of time, wherein the controller controls so as to output an alarm. Inlet concentration of NO _x denitration apparatus for removing NO _x in the exhaust gas, the outlet concentration of NO _x of the NO x removal apparatus, and to measure the concentration of NO _x chimney inlet, the denitration based on concentration of NO _x measurements of the three points It controls ammonia injection amount to the device, outputs an alarm when the concentration of NO _x of the chimney inlet exceeds the operation control value,
The chimney inlet chimney inlet gas analyzer calibration of measuring the concentration of NO _x, during inspection, the inlet concentration of NO _x measurements of the denitration apparatus, and the denitration apparatus on the basis of the outlet concentration of NO _x measured value of the NOx removal system controls ammonia injection amount to, NO _x concentration of said chimney inlet section, flue gas denitration equipment when exceeding the operating control value continuously predetermined interval of time, wherein the controller controls so as to output an alarm Control method.

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